A. Field of the Invention
The present invention relates to a baby walker, particularly to a baby walker speed control caster for a safety concern.
B. Description of the Related Art
The baby walker is commonly used for babies learning to walk. However, most of the conventional baby walkers do not perform a self-braking effect, hence putting the baby in danger when the speed of the baby walker goes too high especially on a downhill or an uneven roadway. Generally, the self-braking device for a baby walker can be realized as the speed control caster.
Referring to FIGS. 1 and 2, a conventional speed control caster 40 for the baby walker generally includes a wheel 41, a ring groove 42 provided at one flank of the wheel 41 and formed with a wavy ball trough 421, a fixing piece 43, a ball 44, a convex shaft tube 45 having a through hole 451 and being integrally formed together with the ring groove 42 at the interior of the caster, and a shaft rod 46.
As shown in FIGS. 1 and 2, the fixing pieces 43 is provided with a central through hole 431 for loosely pivoting with the convex shaft tube 45 such that the fixing pieces 43 is put into the ring groove 42. The shaft rod 46, being formed with a rivet-shaped end 461, is fastened to the pivot holes 401 and 402 of the wheel seat 30 respectively by passing through the through hole 431 and 451 such that the wheel 41 runs by pivoting on the shaft rod 46. Referring to FIG. 2, the ball tough 421 is shaped into three kinds of arcs which are arc 432, protruding arc 433, and concave arc 434 respectively. When the wheel 40 revolves, the ball 44 is pushed forward by the wavy contour of the ball trough 421 such that the ball 44 rolling back and forth a long the ball trough 421 is squeezed between the ring groove 42 and the protruding arc 433 as the ball 44 is swung toward the concave arc 434. As the speed of the caster 40 becomes higher, the frictional force caused between the protruding arc 433 and the ring groove 42 by squeezing the ball 44 gets larger as to result in a braking effect.
The conventional speed control caster 40 is disadvantaged for the following:
1. The frictional force caused between the protruding arc 433 and the ring groove 42 can hardly afford an obvious braking effect for a speed control caster.
2. The protruding arc 433 tends to be deformed after the speed control caster is used for a period of time.
3. The fixing piece 43 does not revolve as the wheel 41 but swing about the convex shaft tube 45, thus hindering the wheel agility at a relatively low speed.
4. The conventional speed control caster has a complex structure resulting in a high-level damage rate and a high manufacturing cost.
One of the objects of the invention is to provide a baby walker speed control caster including an axle piece, a pair of wheels symmetrically provided at either side of the axle piece, and a ball. The axle piece is provided with a pivot hole, a through hole, and a pivot shaft. Each wheel is formed in a thickness radially increasing respectively from the adjacency of the wheel center and is provided with a pivot hole a t the center and a plurality of embossing curves at the inner side; in this way, the wheels are pivotably connected to each other by a pivot axle passing through the pivot holes of the wheels and the axle piece sandwiched between the wheels such that a chamber, containing the ball, is formed by the through hole of the axle piece and the inner walls of the wheels and the width between two inner walls decreases radially from the adjacency of the wheel center. By this structure, a baby walker is effectively braked while in high speed, and the embossing curves leading the ball upward along the elongation of the chamber can hardly diminish the agility of the speed control caster. Besides, the wheels of the speed control caster are also advantaged for the low cost and simple design with a persistent thickness of the wheel, thus maintaining a constant braking effect.